The present invention relates to mineral micronutrient supplements for food products, and to systems and processes for their production. More particularly, the present invention relates to food products incorporating basic copper chloride as a mineral supplement, and to systems and processes for producing such supplements.
Mineral sources, when used at levels consistent with good feeding practices, are important dietary supplements. The need for copper, for example, in poultry and livestock is critical. W. Mertz (Ed.) Trace Elements in Human and Animal Nutrition. Vol I. pp. 301-364 Academic Press, New York (1987). Copper deficiency is a major problem in cattle. Copper tends to form insoluble complexes with molybdenum and sulfide in a cow's rumen, where pH is about 6.0. These complexes remain insoluble through subsequent digestion, even though the pH drops to about 2.5. Thus, there is a need to provide copper supplements in animal feeds where the copper is present in a form in which insoluble complexes cannot form.
A number of copper sources have been approved for use in animal feeds, including, for example, copper sulfate and copper oxide. But current copper sources suffer from a variety of problems. Copper oxide has been shown to have low bioavailability. Copper sulfate, which has adequate bioavailability, often causes instability of desirable organic constituents in a feed mix. Labile nutrients such as vitamins and antibiotics are typically highly susceptible to oxidation. In fact, the dominant destabilizing effect on vitamins in feed mixes is redox reactions by trace minerals. Because copper sulfate has a particularly high water solubility, and because some moisture is inevitably present in feed mixes, copper sulfate tends to create a higher redox potential in the feed mix and release copper ions to catalyze oxidation of vitamins, antibiotics, or other nutrients.
Furthermore, in manufacturing copper-based micronutrient additives for feed products, controlling the particle size of the additive may present problems. Small particle size is generally desirable because small particles can be more easily blended with feed to create a finished feed mix having a relatively uniform distribution of micronutrient additive. However, if particles are too small, a dusting problem is created at the point of blending the additive with the feed, adding manufacturing costs.
With the presence of small particles it is also exceedingly difficult (in some cases nearly impossible) to rinse away the undesirable background constituents from the mother liquor during manufacture of the additive. For example, in manufacturing copper sulfate, the crystallization process is generally operated to produce relatively large crystals to allow free sulfuric acid and other impurities from the mother liquor to be rinsed off more completely. To produce smaller particles for blending into a feed mix, either the copper sulfate crystallization has to be run at suboptimal conditions, or the product has to be ground after formation. This, too, adds manufacturing costs.
The presence of background salts can be exceedingly problematic. For example, ammonium-based background salts may contribute to poor physical characteristics of the micronutrient additive, complicating handling and blending operations. Such salts are typically strongly hygroscopic, and tend to agglomerate when exposed to humid conditions, resulting in the formation of a hydrated, pasty product which is difficult to dewater and to break into a useful powdery material. Moreover, such salts can be highly astringent, which may lead to a reduction in feed intake.
The presence of contaminants in the copper source itself can also be exceedingly problematic. For example, low-cost copper sources often contain contaminants such as arsenic, which complicate separation operations. Furthermore, such a difficult separation operation may significantly increase production costs.
Thus, there is a need to provide a copper-based micronutrient additive which is compatible with vitamins and other nutrients or antibiotics likely to be present in the feed mix, which exhibits excellent bioavailability, and which also has an appropriate particle size.
According to the present invention, a food product is provided. The food product comprising a nutrient blend and, as a source of bioavailable copper, a compound of the formula Cu(OH).sub.x Cl.sub.(2-x). Compounds of this general formula have been referred to as "basic copper chloride." Advantageously, basic copper chloride has low redox potential due to low water solubility, and has high bioavailability.
In accordance with a further aspect of the present invention, a process is provided for producing basic copper chloride from a copper source and a source of chloride ions. The process comprises the steps of retaining a predetermined amount of pre-formed basic copper chloride in a reactor and reacting the copper source and the source of chloride ions in the reactor in the presence of the pre-formed basic copper chloride. In one preferred embodiment, a soluble chloride salt of copper provides both the copper source and the source of chloride ions.
Advantageously, basic copper chloride produced by this process possesses good blending and handling characteristics. The basic copper chloride is produced as a free-flowing powder which can readily be blended into feed mixes for good micronutrient distribution, and which can also be readily blended into fertilizer mixtures. However, the particle size of the basic copper chloride produced by the present process is actually larger than that obtained by the use of previous processes. Background salts can be more easily removed from these larger particles.
In accordance with yet a further aspect of the present invention, a process is provided in which spent etchant streams (e.g., from an operation for manufacturing printed circuit boards) are regenerated to yield basic copper chloride and water-white, reusable ammonium chloride liquor which can be converted into etchant by additional processing. The process comprises the steps of reacting a spent alkaline etchant stream with an acidifying agent at a pH of about 1.8 to about 8.0 to form a product mixture including a copper-containing slurry and an ammonium chloride liquor containing dissolved copper, separating the copper-containing slurry from the ammonium chloride liquor, and contacting the ammonium chloride liquor with a metal scavenger to remove dissolved copper from the ammonium chloride liquor. In one preferred aspect of the process, the acidifying agent is a spent cupric etchant stream.
Advantageously, this process in its preferred embodiments makes use of waste material--preferably a spent cupric etchant stream and a spent alkaline etchant stream--to form a copper-containing slurry from which, for example, basic copper chloride can be recovered. Further advantageously, this process, through the controlled growth of particles, overcomes previous difficulties in removing ammonium chloride, a background salt, from the copper-containing slurry, enabling basic copper chloride to be recovered from the slurry for use as a micronutrient supplement or as a copper source in other products, including fertilizers.
In accordance with yet a further aspect of the present invention, a fertilizer product is provided which comprises a fertilizer blend and a compound of the formula Cu(OH).sub.x Cl.sub.(2-x), wherein x is greater than 0 and less than or equal to 2.0.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived by the inventor.